Final Flashcards
identify the building blocks of DNA
DNA (Deoxyribonucleic acid) is made up of nucleotides
nucleotides have three parts: a sugar, a phosphate group, and a nitrogenous base
describe DNA’s structure and the rules for base pairing
DNA is in a form of a double helix=two strands of DNA twist together with the sugar-phosphate backbone on the outside and nitrogenous base on the inside. (nitrogenous pairs can only pair: adenine–>thymine and guanine–>cytosine)
explain how the template mechanism is important in DNA replication
the template is important in DNA replication because it allows for a complimentary strand to be made (after the two double helix strands separated) so nucleotides can be added and create a new DNA strand
describe the process of DNA replication. explain the “one gene-one polypeptide” hypothesis
- DNA replication is the process of copying the DNA molecule by separating the two strands of the double helix, they use the separated strands as a template called the complimentary strand in order for nucleotides to be added and so DNA polymerase can form bonds and create a new DNA strand
- states that each gene controls the production of a specific polypeptide (scientists know most genes code for the production of a single polypeptide)
trace the information flow from DNA to protein
first, messenger RNA is transcribed from the DNA molecule. an enzyme called RNA polymerase joins the RNA nucleotides together during transcription. RNA splicing removed introns and joins the exams. then it is transferred to the cytoplasm. transfer RNA binds to the mRNA. the process of bringing amino acid into position on the ribosome (ribosomal RNA)
describe how amino acids are coded
transfer RNA (has an amino acid binding site at one end) binds to the mRNA bringing an amino acid into position to be added to the polypeptide (takes place on a ribosome=ribosomal rna)
describe the process of DNA transcription
the DNA sequence is converted to the form of a single strand RNA molecule
describe how RNA is translated to a protein
in the cytoplasm translation converts the nucleic acid sequence into a sequence of amino acids
summarize protein synthesis
the DNA is transcribed in the nucleus, the introns are removed, the exams enter the cytoplasm as mRNA (by translation) the mRNA binds with the tRNA on a ribosome (rRNA)
describe the types of mutations that can affect genes
mutations=a change in a single nucleotide or a change in a large part of a chromosome
- substitution:one nucleotide is replaced by another
- insertion/deletion: one or more nucleotides are added to/removed from a gene
explain what can cause a mutation
errors in crossing over or DNA replication and also a mutagen (physical/chemical agent that causes a mutation)
describe how DNA is packs within the nucleus
first, DNA molecule wraps tightly around small proteins called histones. next, the DNA and the histones wrap into a tight cool. the coil twists again into a thick structure called a “supercoil”
describe the significance of the human genome project
medical researchers use the data to identify genes associated with diseases and to develop treatment for genetic disorders
relate down syndrome and nonseperation/nondisjunction of chromosomes
trisomy 21 which is when a person has three #21 chromosomes. I normally happens because of nondisjunction which is when a pair of homologous chromosomes or sister chromatids fail to separate during meiosis
describe how chromosomes can be damaged
nondisjunction: pair of homologous chomosomes or sister chromatids that fail to seperate
duplication: occurs when a part of chromosome is repeated
deletion: occurs when a part of a chromosome is lost
inversion: occurs when part of a chromosome is reversed
translocation: occurs when a portion of a chromosome attaches to a non-homologous chromosome
summarize the information provided in a pedigree
used to study the inheritance of traits in a human by tracing the occurence of a trait in a family
explain how recessive, dominant, and sex-linked disorders are inherited
recessive: need both alleles to have the disorder, if you have one you are a carrier and none you don’t have it at all
dominant: only need one allele for the disorder to show, if you have none it won’t show
sex-linked: the allele for the trait is located on the X chromosome. males are more at risk than females
describe how it is possible to predict certain genetic disorders
a genetic counselor is a person who is trained to collect and interpret family histories of genetic disorders
Explain how mutations to genes that play a role in regulating the cell cycle can lead to cancer
a mutation can cause a gene to be cancer-causing (oncogene)
explain how the use of bacteria has contributed to the development of DNA technology
biotechnology: involves changing the genomes of organisms using DNA technology
list some of the recent research trends in recombinant DNA technology
medicine, agriculture, and other fields
explain the role of plasmids in engineering bacteria
they use plasmids to move genes into bacteria
explain how biologists “cut and paste” DNA
a restriction enzyme “cuts” a dna molecule into fragments at specific points. Another enzyme “pastes” a fragment carrying a particular gene into a plasmid
describe the procedure used in cloning a specific gene
a restriction enzyme “cuts” a dna molecule into fragments at specific points. Another enzyme “pastes” a fragment carrying a particular gene into a plasmid. The plasmid is put back into a bacterial cell which then reproduces and creates a clone
identify the usefulness of recombinant microorganisms
they create GMO’s that are used often
describe how biologists genetically modify plants and animals
plants: researchers insert a plasmid containing the desired gene
animals: desired gene is inserted into a fertilized egg. the egg is returned to a female animal’s body
explain a technique used to clone animals/plants
plants: cuttings
animals: replacing the nucleus of an egg cell with another cell’s nulceus
summarize the GMO controversy
some people think they are harmful to human health and the environment but some people think they are safe
describe the technique that enables scientists to mass-produce specific segments of DNA in a test tube
polymerase chain reaction is a technique that makes billions of identical DNA molecules in a few hours
describe a technique used to compare DNA samples
Gell electrophoresis is a technique for sorting DNA fragments by length. the shorter fragments sink to the bottom and the larger fragments stay at the top. they can use this to compare DNA samples
explain how operon enable a prokaryote to respond to changes in the environment
in prokaryotes, clusters of genes are controlled by two short stretches of DNA called control sequences. A cluster of genes, along with its two control sequences, is called an operon
summarize the importance of cellular differentiation in the development of an egg into an organism
in organisms with many cells, individual cells become more specialized in structure and function as the organism develops (cellular differentation)
identify unique features of stem cells
they remain undifferentiated but they are cells with the potential to develop into one of several types of differentiated cells
describe a homeotic gene
master control genes that produce proteins that regulate the expression of other genes
summarize ideas from Darwin’s time that influenced his work
evolution: all of the changes that have transformed life over an immense period of time
adaptation: an inherited characteristic that improves an organism’s ability to survive and reproduce in a particular environment
identify some key observations from Darwin’s voyage that led to his theory
theory: evolution
key observations: variation in birds and other organisms
describe the two main points of Darwin’s theory
descent with modification: species living on earth today descended from earlier species
natural selection: process by which individuals with characteristics well-suited to the environment leave more offspring on average than do other individuals
describe information the fossil record contains about life on Earth
fossil record: the collection of fossils recorded in rock layers over time. fossils of extinct species (species that no longer exist) help scientists reconstruct the past. older fossils=buried deeper
tell how the geographic distribution of organisms relates to evolution
where organisms are distributed throughout the world gives clues to how modern species may have evolved
explain how similarities in structure and development among different species are evidence for evolution
similar structures among related species, called homologous structures, provide clues about evolution. Vestigial structures are homologous structures that have a major function in one species but not in a related species. comparing embryos also give clues to evolution when they were similar in closely related species
describe molecular level for evolution
DNA sequences of different species can also be compared. The more similar the sequences, the more recently the species shared a common ancestor
Summarize Darwin’s theory of natural selection
the process by which individuals with inherited characteristics well-suited to the environment leave more offspring on average than do other individuals
compare and contrast natural selection and artificial selection
natural selection: something that just happens and is the second point of evolution
artificial selection: selective breeding of plants and animals to produce offspring with traits that humans value, we control, and supports evolution
relate pesticide resistance in insects to natural selection
pesticides over time do not work because insects adapt to it so people need to keep altering pesticides